G.f. satisfies A(x) = exp( Sum_{k>=1} (2^k + A(x^k)) * x^k/k ).

Terms

a(0) =1a(1) =3a(2) =10a(3) =34a(4) =122a(5) =450a(6) =1723a(7) =6758a(8) =27135a(9) =110913a(10) =460395a(11) =1935233a(12) =8222504a(13) =35255000a(14) =152353021a(15) =662892684a(16) =2901595559a(17) =12768195617a(18) =56450822365a(19) =250637657015